A giant bobble hat which bemused and entertained diners and passers-by outside the city’s branch of Jamie’s Italian has been clumsily stolen in the dead of night by a couple of thieves whose movements were described as “decidedly wobbly” by planners.

The Park Row installation, named Cosy, was made by skilful Sheffield architect Tony Broomhead, pitched as a “rather surprisingly large pompom hat” inspired by the human need for combining fashion with warmth and the insulation requirements of the electric cables inside the box.

The sculpture was swiped in the early hours of Wednesday morning

“Plastic electric insulating sheathing has been knitted into this cheerful, but sadly unwearable item,” cautions the brief for the piece, although the individual who walked off with it seems to have thought otherwise.

CCTV footage, published on YouTube in a bid to secure the return of the haute headpiece, shows a figure immersed in the giant cosy, gingerly navigating a crossing with the aid of an accomplice.

“Please wobbly duo, can you bring it back by Friday?” organisers said on Facebook, as the search stretched into a second day today (June 30 2011).

“The hat’s so big, it obviously covers his face, chest and belly. If you see a massive blue, white and green runaway bobble hat anywhere, please let us know.”

An email sent to the media appealing for its return insisted the incident was not a stunt, although publicists for the project admitted they wished it had been.